Blender crashes when started from the command line
Well the solution for me was to unset my $PYTHONPATH, which was configured to create the output listed above by a line in my ~/.bash_profile file.

When started from the Terminal, Blender now still loads the bundled Python:

found bundled python: /Applications/Blender/blender.app/Contents/MacOS/../Resources/2.74/python


But Python is now able to load the modules it needs. I guess that having $PYTHONPATH set was preventing Blender's Python from being able to load required modules.